R-on-T phenomenon

R-·on-·T phe·nom·e·non

a premature ventricular (QRS) complex in the electrocardiogram interrupting the T wave of the preceding beat; often predisposes to serious ventricular arrhythmias.

R-on-T phenomenon

a cardiac event in which a ventricular stimulus causes premature depolarization of cells that have not completely repolarized. It is noted on the electrocardiogram as a ventricular depolarization falling somewhere within a T wave. The R-on-T phenomenon may result in ventricular tachycardia or ventricular fibrillation.

R-on-T phenomenon

Cardiology A premature ventricular depolarization so early in the cardiac cycle that it falls on the apex of the preceding T wave, possibly presaging ventricular tachycardia or fibrillation; 'R-on-T' indicates a need to ↑ antiarrhythmics–eg, lidocaine

R-on-T phenomenon

a form of ventricular arrhythmia in which the electrocardiographic tracing shows premature ventricular complexes occurring in early diastole. It is believed to lead to ventricular fibrillation in most cases.